Vag-Com Dynoplot

[Doug_RS2]

the ross-tech spreadsheet does something with de-acceleration as well. You have to put your foot on the clutch and let the car slow down to the initial starting speed - I think this takes into account losses (aero and transmission).

This is the part I didn't know how to enter correctly in the spreadsheet - as it takes a lot longer to slow down than accelerate.

If we can get a common test method it will be interesting to compare results - as I do not trust the actual figures.

And it needs a long road to do this in 4th gear - especially the slowing down bit.

There is a link to the file on the forum somewhere - dynoplot.xls - I think Ben posted it.

[S2central.net]

That makes some sense I guess - but we're gonna need to hire an airport runway !


Paul

[S2central.net]

Heheh - see what happens when you miss one thread almost a year ago

I see that Marco has crunched some numbers on this - on a different tack to mine - I started with Energy but he concentrated on force - which I like a lot better.

Marco has also made me want the G-Tech competition meter all that much more now !

Paul

[S2central.net]

And fortunately for my sanity, I see that Marco's derivation for power agrees with mine when you check the math. I had :

Power = (mv^2 - mu^2) / Time

So when u=0 and remember that a = v/t (or v = at when you re-arrange them) I get

Power = m . a^2 . t

The joy in all of this will be unit conversions of course to get Watts into bhp, then we have the doozy calculation of

Torque = (Power x 5252)/RPM

To finish it off. I can feel another spreadsheet coming.

I think we discussed transmission loss befoe wrt the G-Tech boxes. I suspect they assume something in the region of 10-15% loss for 2WD, but I feel that 25% is nearer to the mark for quattro - but the jury is still out. To be honest we should just all talk in power at the wheels instead of the flywheel to get some consistency, but I don't think the G-Tech will do that.


Paul

PS - I'll stop talking to myself now

[Doug_RS2]

We should set up some tests for everyone to do to compare - even the 5th gear 100-200 kph tests will be easy for people without vag-com or a gtech. Then we can have a table of results. I'm sure the RS2 yahoo list had some sort of tests they did.

What are all your measurements in? second/hours or kph or mph ??

[S2central.net]

Any runs I have with VAG-COM will be in seconds and kph but its easy to convert via excel to whatever we need. I'm sure there are on-line calculators out there for this stuff with respect to 1/4 mile times and power estimations from that a la Desktop Dyno and other tools... but I can build whatever we need in Excel.

[JasonS]

What interface do you guys use for VAG-COM? I have one from http://www.andywhittaker.com/ecu/obdii_hardware.htm but it doesn't read my engine codes (does everything else so I am able to reset service indicators..)

[Doug_RS2]

The interface is vag-com by ross-tech - obdII is the interfacec standard - there is probably lots of differnet OBD2 interfaces but vag-com is specific to vag cars.

You can download a trial version to compare it with the one you are using just now - www.ross-tech-com

[Josh-stateside]

I'll be starting my coupe in the next couple weeks, and I am forking out the money for the vag-com pro kit so I'll be able to comment on this later down the road too.

Having the scope tool will be critcal in my opinion for the first start.

Cheers
Josh

[jon_91_s2]

Those are some amazing figures Doug. Any ideas on 0-60/0-100 etc?

[Doug_RS2]

Those are some amazing figures Doug. Any ideas on 0-60/0-100 etc?

I did one run through the gears. 0-60 is 5.4 Seconds - not very impressive. 0-100 is 11.4 seconds.

I think it feels faster than a 5.4 0-60 though.

[jubjub]

I did one run through the gears. 0-60 is 5.4 Seconds - not very impressive. 0-100 is 11.4 seconds.

I think it feels faster than a 5.4 0-60 though.

Surely it must be quicker than that Depending on what review you read a standard RS is anywhere between 5.2(Can't remember)) and 4.8(Evo,Autocar) to 60 . 0-100 comes up in 13.1- this is with 315bhp and 302lbft IIRC.

[audiman]

Well with an approx figure of 370 bhp i pulled a 4.67 0-60mph, that was without dumping the clutch. So I dont think it can be that accurate. Ive been in Dougs car and it 'feels' quicker than that

[Doug_RS2]

Yep - it does feel quicker - I got a good launch as well - dropped at 5500 rpm and in the boost band it just flew - didn't even feel wheelspin (sorry clutch).

The 0-100 time is probably more accurate - what were the speeds people get at the end of a 1/4mile?

[audiman]

not sure, my second run at gti said 3908.7mph!!!! Cant beieve that one somewhow